Shearing fastener for sealing a fastener hole

ABSTRACT

A shearing fastener for sealing a fastener hole in a work piece includes a shank, a plug, and a fastener head. The fastener head is disposed along the upper end of the shank, while the lower end of the shank further includes a transition section that tapers inward and intersects with an upper surface of the plug at a neck. The plug has a threaded outer surface and an outer diameter greater than the shank. The plug engages the threaded bore of the fastener hole when inserted therein. The shank is configured to shear across the neck and separate the shank from the plug when the fastener head is torqued above a threshold torque. The plug is retained within the threaded bore of the fastener hole to seal the lower end of the fastener hole, forming a repaired work piece.

TECHNICAL FIELD

The present disclosure relates generally to a fastener, and moreparticularly to a shearing fastener for sealing a fastener hole.

BACKGROUND

The ability to repair a flaw within the interior of a fastener hole issometimes limited because of the restricted access within the interiorof the hole and the inability to insert tooling to conduct repairs. Inthe context of a cast work piece, core shifts and other castingirregularities can sometimes create thin wall sections adjacent tofastener holes. These thin wall sections are prone to leaks, either byway of material failure at the flaw location or because of porosity ofthe work piece material. This can result in an irreparable work pieceand thus a complete loss of the casting.

Repairing thin wall sections of a work piece generally entails adrilling and tapping process. The thin wall section is drilled, tapped,and then a set screw is inserted into the newly-formed hole to seal thesection and prevent leaks. This process is feasible where the flaw isaccessible. However, for thin wall sections adjacent to fastener holesand internal to the work piece, access is limited for tooling to repairthe flaw both from within the hole and from the interior of the workpiece.

The disclosed shearing fastener is directed to address these and otherproblems.

SUMMARY OF THE INVENTION

In one aspect, the present disclosure is directed to a shearing fastenerfor sealing a fastener hole including a shank, a plug, and a fastenerhead. The shank has an upper end, a lower end, and an outer diameter.The fastener head is disposed along the upper end of the shank and thelower end of the shank includes a transition section that tapers inwardto a neck that intersects with an upper surface of the plug. The plughas a threaded outer surface and an outer diameter that is greater thanthe outer diameter of the shank.

In another aspect, the present disclosure is directed to a method ofsealing a fastener hole in a work piece that includes threading ashearing fastener into a threaded bore of the fastener hole, theshearing fastener including a shank, a plug, and a fastener head. Theshank has an upper end, a lower end, and an outer diameter. The fastenerhead is disposed along the upper end of the shank, while the lower endof the shank further includes a transition section that tapers inward toa neck disposed along an upper surface the plug. The plug has a threadedouter surface that engages the threaded bore and an outer diameter thatis greater than the outer diameter of the shank. The method furtherincludes rotating the fastener head of the shearing fastener until itsplug bottoms out in the threaded bore. Then torque is applied to thefastener head sufficient to shear a neck of the shearing fastener toseparate its shank from the plug. The shank is then removed from thethreaded bore, retaining the plug within the threaded bore.

In yet another aspect, the present disclosure is directed to a repairedwork piece having a fastener hole with a sealed bore made by a processincluding the steps of threading a shearing fastener into a threadedbore of the fastener hole. The shearing fastener includes a shank, aplug, and a fastener head. The shank also has an upper end, a lower end,and an outer diameter. The fastener head is disposed along the upper endof the shank, while the lower end of the shank further includes atransition section that tapers inward to a neck disposed along an uppersurface the plug. The plug has a threaded outer surface that engages thethreaded bore and an outer diameter that is greater than the outerdiameter of the shank. The fastener head of the shearing fastener isrotated until its plug bottoms out in the threaded bore. A torque isapplied to the fastener head sufficient to shear a neck of the shearingfastener to separate its shank from the plug, after which the shank isremoved from the threaded bore and the plug is retained within thethreaded bore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an exemplary work piece with afastener hole and thin wall section at the bottom of the fastener hole;

FIG. 2 is a side elevation view of an exemplary disclosed shearingfastener;

FIG. 3 is a cross-sectional view of the exemplary shearing fastener ofFIG. 2;

FIG. 4 is a close-up of the cross-sectional view of the exemplaryshearing fastener of FIG. 2; and

FIG. 5 is a cross-sectional view illustrating an exemplary repaired workpiece using a disclosed method of operating the shearing fastener ofFIG. 2.

DETAILED DESCRIPTION

FIG. 1 illustrates an exemplary fastener hole 40 disposed within a workpiece 100. In various exemplary implementations of the apparatus andmethod according to this disclosure, the work piece may be any parthaving a fastener hole, including an engine block. The fastener hole 40has an open upper end 41, interior walls 44, and an interior volume 43.The fastener hole 40 is generally a tapped hole extending through anupper surface 107 of the work piece 100 with threads 45 along itsinterior walls 44. A tap is used to create the threads 45, where the tapsometimes stops short of a lower end 42 of the fastener hole. In theseinstances, a smooth wall section 48 can be present along the lower end42 of the hole 40. The length of threads 45 along the walls 44 of thefastener hole 40 and the size of its interior volume 13, however, enablethe fastener hole 40 to receive a threaded fastener therein. To receivethe threaded fastener, the fastener hole 40 has a defined diameter,depth, and thread pitch that are all complementary to the threadedfastener.

An exemplary fastener hole 40 of the present disclosure is a fastenerhole with an enclosed lower end 42 as presented in FIGS. 1 and 5.Enclosed fastener holes, or blind fastener holes, do not pass completelythrough the work piece 100. While these types of fastener holes 40 areillustrative of potential applications for the apparatus and techniquesdisclosed herein, the disclosure is not limited to sealing enclosed orblind fastener holes.

Creating fastener holes in a work piece can create flaws if the holesare improperly located or the work piece has shifted duringmanufacturing. In particular, fastener holes 40 such as shown in FIG. 1may be drilled too closely to an interior cavity 108 within the workpiece. This locates the lower end 42 of the fastener hole 40 a shortdistance away from an interior wall 105 within the work piece, resultingin a thin wall section 115 between the interior cavity 108 and thefastener hole 40. These thin wall sections 115 may have a dimension 110(i.e. a material thickness) smaller than design limits allow. This canlead to premature structural failure at this location or fluidpass-through by way of material porosity and short travel distance.

FIG. 2 illustrates a side view of an exemplary shearing fastener of thepresent disclosure. The shearing fastener 10 includes a shank 15, a plug50, and a fastener head 30. The shank 15 is an elongated member with anupper end 18 and a lower end 19. In one embodiment, the shank 15 formsan elongated cylindrical member with an outer profile 16 having a smoothsurface. The outer profile 16 of the shank 15 has an outer diameter thatmay be uniform along its length and configured to be less than thediameter of the fastener hole 40. This allows the outer profile of theshearing fastener 10 to be inserted into the fastener hole without theshank 15 engaging the threads 45 of the fastener hole 40, while alsobeing sized to he received without interference into the interior volume43 of the fastener hole 40.

As shown in FIGS. 2-4, the lower end 19 of the shank 15 includes atransition section 21 that tapers inward to a neck 25 that intersectsthe plug 50. The plug 50 extends outward and has an outer diameter 68that is greater than the diameter of the shank 20 along its length. Theplug 50 has a threaded outer surface 53 along its outer diameter that isconfigured to engage the threads 45 of the fastener hole 40. In thismanner, the threaded outer surface 53 of the plug 50 is configured toengage the threads 45 of a fastener hole 40 while the smaller-diametershank 15, with its smooth outer profile, is received within the holewithout engaging the hole threads 45. The shank 15 therefore connects tothe plug 50 and drives the plug 50 into the fastener hole 40 byappropriate rotation of the shank 15.

Along the upper end 18 of the shank is a fastener head 30 that has anupper surface 31. The fastener head 30 is configured to connect to atorqueing tool, such as a wrench, driver, or another suitable tool forapplying a rotation to the fastener head 30. In one example, the uppersurface 31 of the fastener 10 may have a depression forming a hexagonalsocket, a Phillips head socket, a torx socket, or the like.Alternatively, the sides of the fastener head 30 may be faceted to allowa wrench, socket, or similar torqueing tool to apply a rotation andtorque to the outer surface 33 of the fastener head. The rotationapplied to the fastener head 30 via the particular tool imparts arotation on the shank 15 and a like rotation on the plug 50, driving theplug 50 into the fastener hole 40 when the complementary threads of thefastener hole 40 and plug 50 are aligned. As the head 30 is rotated, theplug 50 rotates and is drawn into the interior volume 43 of the hole 40.

FIGS. 3 and 4 show side section views of the exemplary shearing fastener10 of the present disclosure at the intersection of the shank 15 and theplug 50. The lower end 19 of the shank 15 has a transition section 21that tapers inward, reducing the diameter of the shank 20 untilintersecting with the plug 50. The transition section 21 tapers thediameter of the shank 20. In one embodiment, the transition section 21may taper the shank 15 equally around the periphery of the shank 15 andlinearly until the shank 15 intersects an upper surface 52 of the plug50. The intersection between the shank 15 and the plug 50 forms a neck25, which has a neck diameter 26. The neck diameter 26 is smaller thanthe diameter of the shank 15 and the transition section 21 tapers thelower end 19 of the shank to the neck 25. Therefore, the neck 25 has asmaller cross-sectional area than the cross-sectional area of the shank15 along its upper end 18.

The plug 50 further includes an upper surface 52, a height 80, an upperextent 81, and a lower extent 82. The upper surface 52 of the plug inone embodiment is not planar and not coincident with the upper extent 81of the plug across its surface area. Rather, the upper surface 52 mayinclude a recess 59 that extends into the plug 50 and below its upperextent 81. The upper surface 52 may be aligned with the upper extent 81of the plug 50 along the outer periphery of the upper surface 52, whilethe recess 59 extends downward into the plug at the intersection of thetransition section 21 and the plug upper surface 52. The transitionsection 21 of the shank 15 intersects the plug 50 at the neck 25. Theneck 25 is disposed within the recess 59 and below the upper extent 81of the plug. Therefore the neck 25 is disposed within the interior ofthe plug's height 80 (i.e. below its upper extent 81).

Additionally, the plug 50 may have a round outer profile 56 with athreaded outer surface 53. The threads 53 extend around the round outerprofile 56 of the plug and along the height 80 of the plug. Along theupper corner 54 and lower corner 64 of the plug, material may be removedso the corners 54, 64 are chamfered. This eliminates right-angletransitions between the outer profile 56 of the plug and the uppersurface 52, and between the outer profile 56 and a lower surface 51. Thechamfered corners 54, 64 facilitate insertion of the plug 50 into theopen upper end 41 of the fastener hole 40, and further prevent the plug50 from catching any burrs or flaws within the interior of the fastenerhole 40 while being threaded therein.

Along the upper surface 52 of the plug is the recess 59. The recess 59is a cavity formed between the transition section 21 of the shank 15 andan angled surface 57 extending downward from the upper extent 81 of theplug 50 along its upper surface 52. The transition section 21 of theshank 15 and the angled surface 57 converge at a radius 58 along theperimeter of the neck 25. This radius 58 forms an acute angle or “sharp”angle that is configured to create a stress riser or stressconcentration when the fastener 10 is subjected to physical load. Astress riser is an area that experiences particularly high stresses orconcentrations of stress when a part is subjected to load. The stressriser created by the radius 58 therefore forms a designed weak pointacross the neck 25, and therefore a weak point between the shank 15 andthe plug that can be used as a designed separation plane. In particular,the radius 58 extending around the periphery of the neck 25 at thesmallest diameter section of the transition section 21 (i.e. the neck)forms a shear plane across the neck. This is a designed failure locationand is used to separate the shank 15 from the plug 50 at the neck 25when the shank is subjected to a threshold torque. This shear planeextends across the neck 25 and may be disposed within the recess 59below the upper extent 81 of the plug 50.

Described in more detail the neck 25 is a designed failure locationbetween the shank 15 and the plug 50 such that the two separate when athreshold stress develops at the radius 58 and across neck 25. In apreferred embodiment, the designed stress riser, at the radius 58 at theintersection of the transition section 21 and the plug 50, develops ahigher concentration of stress than the rest of the fastener 10 when thefastener is subjected to load at the fastener head 30. The placement ofthe radius 58 adjacent to the small-diameter neck 25 forms a designedshear plane across the neck 25. The shank 15 and the plug 50 separateacross the neck 25 when sufficient shear load develops at this location.This facilitates a particular mode of failure, in which the shank 15will separate from the plug 50 and the failure point will be across theneck 25 and below the plug upper extent 81. Any barbs or burrs thatinadvertently develop at the neck 25 at failure will therefore bemaintained within the recess 59 and not protrude above the plug upperextent 81. This is particularly useful when maximizing available spacein a fastener hole by preventing protruding burrs from consuming anyuseful space.

The shear force used to separate the shank 15 from the plug 50 isgenerally introduced by a torque applied to the fastener head 30. Thethreshold torque, or torque necessary to shear the shank 15 from theplug 50 at the neck 25, will be dependent on several factors. Theseinclude primarily the ultimate stress of the fastener material and thediameter of the neck 25. The choice of material used to form thefastener (i.e. stainless steel, etc.) and the method in which thematerial is manufactured (i.e. forged, etc.) will dictate the ultimatestress. The designed diameter of the neck 25 for failing at a specificshear load (i.e. threshold torque) will be dependent on the diameter ofthe fastener hole 40, which will limit the neck diameter 26. Therefore,the threshold torque required to separate the shank 15 from the plug 50will be based on the dimensions, material, and design limitations of theparticular application.

With respect to forming the shearing fastener 10 of the presentdisclosure, several methods are contemplated. In one process, the recess59 is formed in the upper surface 52 of the plug using a millingprocess. In an embodiment, a carbide bit of a milling machine, oranother type of bit driven by another suitable machine, is plunged at anangle into the area forming the recess 59 between the plug 50 and shank15 to remove material. At the same time, this same cutting process formsthe radius 58 around the periphery of the neck 25. The radius 58 is atight bend or sharp radius as described above, forming the stress riseraround the perimeter of the neck 25. At the same time, the millingoperation also forms the transition section 21 at lower end 19 of theshank 15 and the angled surface 57 in the upper surface 52 of the plug.The bit, having a substantially conical cutting surface, forms theradius 58 at the same time the recess 59 and transition section 21 arecut. The conical bit, shown by the conical cut lines 90 in FIG. 3,defines the profile of the recess 59, the transition section 21, and theradius 58 in one operation. While this is one method of manufacturing,other operations are also contemplated for forming these features. Thedisclosed milling operation is but one process that is not intended tobe limiting.

Along with the disclosed milling operation, the shearing fastener of thepresent disclosure may also be formed from an existing threadedfastener. In one embodiment, an existing threaded fastener can be usedas the basis for forming the smooth shank, threaded plug, andintersection between the two. The existing fastener is turned on a lathor milling machine to remove the threads from its shank and to reduceits diameter. This process is conducted along the shank and below itsfastener head, and stops short of a distal end of the shank. This leavesa section of threads remaining for forming the new plug. Once turned, acutting bit can be plunged into the intersection of the smooth shank andthe plug to form the radius and recess. The result is a smooth surfaceshank and a threaded plug with the radius and transition sectiondescribed above.

In an alternative embodiment, the shearing fastener of the presentdisclosure may be formed from scratch using a rolled forging technique.The rolled forging is heat treated and machined to form the shank andplug. The rolled forging is rolled using a tool to form the threads ofthe plug. Machining operations can then form the recess and radius.

INDUSTRIAL APPLICABILITY

The disclosed shearing fastener may be applicable to any work piecehaving a fastener hole. This includes work pieces where a fastener holeis adjacent to an interior cavity within the work piece, and a thin wallsection exists between the bottom of the fastener hole and the cavity.The thin wall section occurring at the bottom of a threaded fastenerhole may be subject to failure or may create potential locations forleakage. Example work pieces include engine blocks with fastener holesimproperly located adjacent to interior coolant passages. This can occurwhen technicians drill fastener holes in the block and misplace theirlocations. This can also result from an improper design or shifts duringthe block casting process, in which irregularities in the block areformed. In any case, when this occurs and a fastener hole is too closeto an interior passage, the block is generally scrapped and a new blockmust be cast.

The disclosed shearing fastener can be installed into a threadedfastener hole of a machine component using standard tools, The shearingfastener facilitates the repair of a thin wall section at the bottom ofthe fastener hole by sealing the lower end of the fastener hole with aplug portion of the fastener configured to break off from the rest ofthe shearing fastener at a threshold torque. By sealing the hole, anythin wall section between the fastener hole and an interior cavity inthe work piece will not result in fluid pass-through or leakage into thefastener hole. The following description sets forth an exemplaryimplementation of a repair method using the disclosed shearing fastener.

As shown in FIG. 5, when a work piece 100 is inspected and either aninterior failure or thin wall section 115 is found adjacent to afastener hole 40, the shearing fastener 10 of the present disclosure canbe used to seal the lower end 42 of the fastener hole 40. The plug 50 ofthe shearing fastener 10 is ideally positioned within the lower end 42of the hole 40. This retains sufficient volume 43 within the hole 40 andthus a sufficient number of threads 45 along the walls 44 of the hole 40to grip a subsequent fastener inserted above the plug 50 after the plug50 has been positioned and separated from the shank 15.

To place the plug 50 within the lowermost portion of the hole lower end42, additional threads 45 may need to be added. As described previously,the original tapping of the hole 40 may leave a smooth wall section 48along the lower end 42 of the fastener hole 40. To ensure the plug 50can thread to the lower end 42 of the fastener hole, a bottoming tap canbe inserted to cut additional threads 45 along the smooth wall section48 as shown in FIG. 5. This ensures the plug 50 will bottom out as farinto the fastener hole 40 as possible to retain sufficient room abovethe plug 50 for a subsequent fastener.

The threaded outer surface 53 of the plug 50 is configured to engage thefemale threads 45 of a fastener hole 40, while the shank 15 isconfigured to shear across the neck 25 and form a fracture surface 28across the neck 25 when separating the shank 15 from the plug 50. Toseparate the shank 15 from the plug 50, the fastener head 30 is torquedabove a threshold torque necessary to develop shear across the neck 25sufficient to fail the part at this location.

To seal the hole 40 and separate the plug 50 from the shank 15, the hole40 may first need to be prepared by adding additional threads to thelower end 42 of the hole 40 using the bottoming tap described above. Theshearing fastener 10 is then inserted into the open upper end 41 of thefastener hole 40. The threaded outer surface 53 of the plug 50 isthreaded onto the complementary threads 45 of the. fastener hole 40. Atool is used to advance the plug 50 into the hole 40 by rotating thefastener head 30 until the plug 50 reaches the lower end 42 of the hole40 and the end of the threads 45 therein. The plug 50 is thusbottomed-out in the threaded bore of the hole 40 as far as the threads45 and geometry of the hole will allow.

The fastener head 30 is then torqued using a tool that applies a torqueto the fastener head 30. The torque is transmitted from the fastenerhead 30 to the shank 15 and thus to the neck 25 and the plug 50. As thefastener head 30 is torqued, torsional stress develops in the shank 15and the neck 25 at the intersection of the neck with the plug. Once theplug 50 has bottomed-out in the hole 40, the stress becomes concentratedin the neck 25 because of the radius 58 and the cross-sectional area ofthe neck 25. The torque applied to the fastener head results in aconcentrated shear load across the neck 25, where the shear load willcause the material across the neck 25 to fail when a sufficient shearload develops. Therefore, a torque is applied to the fastener head 30sufficient to shear the neck 25 to separate the shank 15 from the plug50. Once the threshold torque is reached, the shear load across the neck25 will fail the shearing fastener across the neck 25 and separate theshank 15 from the plug 50.

Once the threshold torque is applied and the neck 25 fails, the shank 15is separated from the plug 50. The shank 15 can then be removed from thethreaded bore of the hole 40. The plug 50 is retained within thethreaded bore of the hole 40 along its lower end 42. The torque appliedto the plug 50 ensures that the plug 50 will remain within the lower end42 and will not become unseated. To further ensure this, an anaerobicthread locker material can be added to the threaded outer surface 53 ofthe plug 50 prior to the shearing fastener 10 being inserted into thehole 40. The anaerobic thread locker material cures in the absence ofoxygen, and thus seals the threaded outer surface 53 of the plug 50 tothe thread 45 of the hole 40 when the plug 50 is seated within the lowerend 42.

Once seated, the plug 50 forms a seal along the lower end 42 of the hole40. The lower surface 51 of the plug 50 extends across the bore of thehole 40, while the threaded outer surface 53 of the plug 50 and anyadditional thread-locking compound seals the lower end 42 of the hole.This prevents leakage of fluid from any interior passageways or cavities108 in the work piece, which can occur in the event of material failureat the thin wall section 115 or leakage across the thin wall section115. Thus, the work piece will not leak through the fastener hole 40when a pressurized or non-pressurized fluid is present in an interiorcavity 108 adjacent to the fastener hole 40.

As illustrated in FIG. 5, in a preferred embodiment, the fracturesurface 28 of the neck 25 after being separated from the shank 15 isbelow an upper extent 81 of the plug 50. That is, the neck 25 ispositioned along the upper surface 52 of the plug 50 within a recess 59,below an upper extent 81 of the plug 50. This ensures the fracturesurface 28 is disposed within the interior of the plug 50 and no portionof the fracture surface 28 extends above the plug 50. This maximizesroom within the bore of the hole 40 and minimizes the volume consumed bythe plug 50.

In addition, the chamfered corners 54, 64 of the plug 50 prevent theplug 50 from catching burrs or imperfections within the threaded bore ofthe hole 40, This prevents the plug 50 from catching in the hole 40before reaching the lower end 42. This would create a situation in whichthe plug 50 may have to be removed from the hole 40 to clean threads 45of the hole 40, or may cause the installer to apply a greater torque tothe fastener head 30 to overcome the obstruction. This can result inunnecessary stress developing in the neck 25 before the plug 50 bottomsout, thus creating the risk of premature failure across the neck 25before the plug bottoms out. This would reduce the useable volume in thebore of the hole 40, necessitating a smaller fastener above the plug 50or an operation to remove the plug 50. Neither of these is preferred.

Several advantages may be achieved with the shearing fastener of thepresent disclosure. First, the shearing fastener makes it possible toinsert a plug 50 within the threaded bore of a fastener hole 40 to plugany potential leaks. Thus, entire work pieces can be saved and preventedfrom being scrapped if a fastener hole 40 is located too close to aninternal cavity 108. A repaired work piece 200, as shown in FIG. 5, canbe achieved by the process described above, where the shearing fastener10 is inserted into the threaded bore of the fastener hole 40, bottomedout, and then torqued above a threshold torque to separate the plug 50from its shank 15. The plug 50 seals the hole and prevents unwantedleakage through the fastener hole 40, and thus allows for a repairedwork piece 200. This prevents material waste, prevents economic waste,and reduces lost time. The threaded bore of the fastener hole 40 becomesa sealed bore, and the work piece can be used as intended despite theproximity of the hole 40 to an interior cavity 108.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the shearing fastener of thepresent disclosure. Other embodiments will be apparent to those skilledin the art from consideration of the specification and practice of thedisclosed shearing fastener. It is intended that the specification andexamples be considered as exemplary only, with a true scope beingindicated by the following claims and their equivalents.

What is claimed is:
 1. A shearing fastener for sealing a fastener hole,comprising: a plug having an upper surface and a threaded outer surface;a shank having an upper end, a lower end, and a diameter; a transitionsection along the lower end of the shank that tapers inwardly andintersects the upper surface of the plug at a neck; and a fastener headdisposed along the upper end of the shank; wherein the plug has an outerdiameter that is greater than the diameter of the shank.
 2. The shearingfastener of claim 1, wherein the plug is configured to engage femalethreads of a fastener hole, and the shank is configured to shear acrossthe neck to separate the shank from the plug when the fastener head istorqued above a threshold torque.
 3. The shearing fastener of claim 1,wherein the upper surface of the plug further includes a recess and thetransition section intersects the plug below an upper extent of theplug.
 4. The shearing fastener of claim 1, wherein: the upper surface ofthe plug further includes a recess and the transition section intersectsthe plug below an upper extent of the plug; the plug being configured toengage female threads of a fastener hole, and the shank being configuredto shear and form a fracture surface across the neck to separate theshank from the plug when the fastener head is torqued above a thresholdtorque; the fracture surface being below the upper extent of the plug.5. The shearing fastener of claim 1, further including: a radiusextending around a periphery of the neck at the intersection between thetransition section and the upper surface of the plug.
 6. The shearingfastener of claim 5, wherein the radius further includes an acute anglebetween the transition section and the upper surface of the plug.
 7. Theshearing fastener of claim 1, further including: a radius extendingaround a periphery of the neck at the intersection between thetransition section and the upper surface of the plug; the upper surfaceof the plug including a recess extending around the periphery of theneck such that at least a portion of the neck is disposed below an upperextent of the plug, the recess including an angled surface extendingdownward from the upper extent of the plug to the radius.
 8. Theshearing fastener of claim L wherein: the outer surface of the plugfurther includes an upper corner and a lower corner that are chamfered.9. The shearing fastener of claim 1, wherein: the neck has a smallercross-sectional area than a cross-sectional area of the upper end of theshank.
 10. A method of sealing a fastener hole in a work piece,comprising: threading a shearing fastener into a threaded bore of thefastener hole, the shearing fastener comprising: a plug having an uppersurface and a threaded outer surface; a shank having an upper end, alower end, and a diameter; a transition section along the lower end ofthe shank that tapers inwardly and intersects the upper surface of theplug at a neck; and a fastener head disposed along the upper end of theshank; wherein the plug has a threaded outer surface that is configuredto engage the threaded bore and an outer diameter that is greater thanthe diameter of the shank; rotating the fastener head until the plugbottoms out in the threaded bore; applying a torque to the fastener headsufficient to shear the neck of the shearing fastener to separate theshank from. the plug; removing the shank from the threaded bore; andretaining the plug within the threaded bore.
 11. The method of claim 10,further including: before the step of threading the shearing fastenerinto the threaded bore, inserting a bottoming tap into the threadedbore; and cutting additional threads into the threaded bore along alower end thereof.
 12. The method of claim 10, further including:applying an anaerobic thread locker material to the threaded outersurface of the plug before the step of threading the shearing fastenerinto the threaded bore.
 13. The method of claim 10, wherein the neck ofthe shank is disposed within a recess along the upper surface of theplug and the step of applying torque to the fastener head sufficient toshear the neck creates a fracture surface within the recess and below anupper extent of the plug.
 14. The method of claim 10, wherein theshearing fastener further includes a radius extending around a peripheryof the neck at the intersection between the transition section and theupper surface of the plug.
 15. The method of claim 14, wherein theradius further includes an acute angle between the transition sectionand the upper surface of the plug. 16, A repaired work piece having afastener hole with a sealed bore, the repair of the work piece made by aprocess comprising: threading a shearing fastener into a threaded boreof the fastener hole, the shearing fastener comprising: a shank, a plug,and a fastener head; the shank having an upper end, a lower end, and adiameter; the fastener head being disposed along the upper end of theshank; the lower end of the shank further comprising a transitionsection that tapers inward and intersects with an upper surface the plugat a neck; wherein the plug has a threaded outer surface that engagesthe threaded bore and an outer diameter that is greater than thediameter of the shank; rotating the fastener head until the plug bottomsout in the threaded bore; applying a torque to the fastener headsufficient to shear the neck of the shearing fastener to separate theshank from the plug; removing the shank from the threaded bore; andretaining the plug within the threaded bore to make the sealed bore. 17.The repaired work piece of claim 16, wherein: before the step ofthreading the shearing fastener into the threaded bore, inserting abottoming tap into the threaded bore; and cutting additional threadsinto the threaded bore along a lower end thereof.
 18. The repaired workpiece of claim 16, further including: applying an anaerobic threadlocker material to the threaded outer surface of the plug before thestep of threading the shearing fastener into the threaded bore.
 19. Therepaired work piece of claim 16, wherein the neck of the shank isdisposed within a recess along the upper surface of the plug and thestep of applying torque to the fastener head sufficient to shear theneck creates a fracture surface within the recess and below an upperextent of the plug.
 20. The method of claim 16, wherein the shearingfastener further includes a radius extending around a periphery of theneck at the intersection between the transition section and the uppersurface of the plug.